Despite having its roots in ancient Greece,
the theory of evolution was first brought to the attention
of the scientific world in the nineteenth century. The most
thoroughly considered view of evolution was expressed by the
French biologist Jean-Baptiste Lamarck, in his Zoological
Philosophy (1809). Lamarck thought that all living things
were endowed with a vital force that drove them to evolve
toward greater complexity. He also thought that organisms
could pass on to their offspring traits acquired during their
lifetimes. As an example of this line of reasoning, Lamarck
suggested that the long neck of the giraffe evolved when a
short-necked ancestor took to browsing on the leaves of trees
instead of on grass.

This evolutionary model of Lamarck's was invalidated
by the discovery of the laws of genetic inheritance. In the
middle of the twentieth century, the discovery of the structure
of DNA revealed that the nuclei of the cells of living organisms
possess very special genetic information, and that this information
could not be altered by "acquired traits." In other words,
during its lifetime, even though a giraffe managed to make
its neck a few centimeters longer by extending its neck to
upper branches, this trait would not pass to its offspring.
In brief, the Lamarckian view was simply refuted by scientific
findings, and went down in history as a flawed assumption.

However, the evolutionary theory formulated by
another natural scientist who lived a couple of generations
after Lamarck proved to be more influential. This natural
scientist was Charles Robert Darwin, and the theory he formulated
is known as "Darwinism."